Surgical fastener applying apparatus

ABSTRACT

A surgical fastener applying apparatus for applying fasteners to body tissue. The apparatus includes a cartridge receiving half-section defining an elongated channel member configured to releasably receive a stationary housing of a firing assembly. The stationary housing is dimensioned to releasably receive a single use loading unit therein, and includes a lockout structure that prevents insertion of the single use loading unit into the stationary housing after the stationary housing is mounted to the cartridge receiving half-section.

This application claims priority from provisional application No.61/521,074 filed, Aug. 8, 2011, the entire contents of which areincorporated herein by reference.

BACKGROUND

1. Technical Field

The present disclosure relates to a surgical fastener applying apparatusand, more particularly, to a surgical fastener applying apparatus havingreusable and disposable components.

2. Discussion of Related Art

Surgical fastener applying apparatus, wherein tissue is first grasped orclamped between opposing jaw structures and then joined by means ofsurgical fasteners, are well known in the art. In some such apparatus, aknife is provided to cut the tissue which has been joined by thefasteners. The fasteners are typically in the form of surgical staples,although, other surgical fasteners may also be utilized, such as, forexample, clips or two part polymeric surgical fasteners.

Surgical fastener applying apparatus typically include two elongatedbeam members which are used to capture or clamp tissue therebetween.Typically, one of the beam members carries a disposable cartridgeassembly which houses a plurality of staples arranged in at least twolateral rows, while the other beam member includes an anvil whichdefines a surface for forming the staple legs as the staples are drivenfrom the cartridge assembly. Where two part fasteners are used, the beammember which includes the anvil carries a mating part of the two partfastener, e.g. the receiver. Generally, the staple formation process isaffected by the interaction between one or more longitudinally movingcamming members and a series of individual staple pushers. As thecamming members travel longitudinally through the cartridge carryingbeam member, the individual pusher members are biased upwardly into abackspan of the staples supported within the cartridge assembly tosequentially eject the staples from the cartridge. A knife may beprovided to travel with the camming members between the staple rows tocut the tissue between the rows of formed staples. An example of such aninstrument is disclosed in U.S. Pat. No. 7,631,794, which isincorporated herein in its entirety by reference.

Because of the dangers associated with improper sterilization, apparatusare typically disposable after use. Although the cartridge assembly maybe replaced to perform multiple fastener applying operations on a singlepatient, the staple applying apparatus is typically disposable after asurgical procedure has been completed. This requirement of disposabilitymay increase the costs associated with surgical procedures. Althoughreusable fastener applying apparatus have been developed, such apparatuscan be overly complex and prove difficult to sterilize.

A need exists in the art for a fastener applying apparatus whichincludes reusable components, is not overly complex and is configured tofacilitate proper sterilization after use in a surgical procedure.

SUMMARY

The present invention relates to a surgical fastener applying apparatusfor applying surgical fasteners to tissue. In one aspect of the presentdisclosure, a surgical fastener applying apparatus is providedcomprising an anvil half-section including a distal anvil portion and aproximal handle portion, a cartridge receiving half-section defining anelongated channel member, and a stationary housing. The stationaryhousing is configured to be releasably supported within the elongatedchannel member of the cartridge receiving half-section. The stationaryhousing supports firing components of the apparatus. The stationaryhousing is also dimensioned to releasably receive a single use loadingunit. The stationary housing includes a lockout structure that preventsfull insertion of the single use loading unit into the stationaryhousing after the stationary housing is mounted to the cartridgereceiving half-section.

The lockout structure in some embodiments may define a first positionwhich prevents insertion of the single use loading unit into thestationary housing, and a second position which allows insertion of thesingle use loading unit into the stationary housing. The lockoutstructure is configured to move between its first position and itssecond position. However, the lockout structure is obstructed frommoving from the first position to the second position when thestationary housing positioned within the elongated channel member.

In one embodiment, the lockout structure is positioned on a centralportion of the stationary housing. The lockout structure in someembodiments includes a pair of sidewalls and a pair of flanges extendingfrom the top of each sidewall such that when the lockout structure is inthe first position, the sidewalls are substantially parallel withrespect to each other, and the flanges define a lateral dimension oropening therebetween which is less than the lateral dimension of thesingle use loading unit to prevent entry of the single use loading unittherein, and when the lockout structure is in the second position, thesidewalls are inclined away from each other, and the flanges define alateral dimension or opening therebetween which is larger than thelateral dimension of the single use loading unit to permit entry of thesingle use loading unit therein.

In some embodiments, the sidewalls of the central portion are connectedto proximal and distal portions of the stationary housing by livehinges, such that the sidewalls of the central portion are pivotablewith respect to the proximal and distal portions. In other embodiments,the lockout structure includes a bottom surface, and the sidewalls arehingedly attached to the bottom surface.

In another aspect, the present disclosure provides a surgical fastenerapplying apparatus comprising a reusable anvil half-section, a reusablecartridge receiving half-section, and a disposing firing assemblyconfigured to be releasably supported within the cartridge receivinghalf section. The firing assembly includes a disposable pusher assemblyand a disposable single use loading unit operably mountable to thepusher assembly, wherein the single use loading unit is not operablymountable to the pusher assembly if the pusher assembly is mounted inthe cartridge receiving half section.

In some embodiments, the surgical fastener apparatus further comprisesfirst and second members extending from the pusher assembly movablebetween a first position having a first gap dimensioned to preventinsertion of the single use loading unit and a second position having asecond gap larger than the first gap and dimensioned receive the singleuse loading unit. In some embodiments, the first and second membersextend from first and second sidewalls of the pusher assembly. In someembodiments, the first and second members are normally in the secondposition.

In another aspect, the present disclosure provides a disposable firingassembly for use with a surgical fastener applying apparatus comprisinga disposable single use loading unit and a disposable pusher assembly.The firing assembly is insertable into a cartridge receiving halfsection of the fastener applying apparatus and the single use loadingunit is operably mountable to the pusher assembly, wherein the pusherassembly includes a lockout member movable from a first blockingposition preventing operable insertion of the single use loading unittherein and a second position enabling operable insertion of the singleuse loading unit therein.

In some embodiments, the lockout member is biased to the first position,and the lockout member is prevented from moving to the second positionwhen the pusher assembly is mounted within the cartridge receiving halfsection. In some embodiments, the lockout member includes first andsecond members extending inwardly toward a longitudinal axis of thepusher assembly and movable to vary a gap therebetween. In someembodiments, the first and second members pivot from a positionsubstantially perpendicular to the longitudinal axis to a first positioninclined with respect to the longitudinal axis.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the presently disclosed surgical fastenerapplying apparatus will now be described herein with reference to theaccompanying figures wherein:

FIG. 1 is a side perspective view from the distal end of one embodimentof the presently disclosed surgical fastener applying apparatus in theclamped position;

FIG. 2 is a side perspective view from the proximal end of the surgicalfastener applying apparatus shown in FIG. 1 in the clamped position;

FIG. 2A is a side perspective view of the surgical fastener applyingapparatus shown in FIG. 1 in the open position;

FIG. 2B is an enlarged view of the indicated areas of detail shown inFIG. 2A;

FIG. 3 is a side perspective view with parts separated of the surgicalfastener applying apparatus shown in FIG. 1;

FIG. 3A is a side cross-sectional view of the clamp lever of thefastener applying apparatus shown in FIG. 1;

FIG. 4 is a side perspective view of the cartridge receivinghalf-section of the surgical fastener applying apparatus shown in FIG. 1with the single use loading unit and the firing assembly supportedwithin the cartridge receiving half-section;

FIG. 5 is an enlarged view of the indicated area of detail shown in FIG.4;

FIG. 6 is a perspective view from above of the cartridge receivinghalf-section of the surgical fastener applying apparatus with the SULUand the firing assembly supported therein;

FIG. 7 is an enlarged view of the indicated area of detail shown in FIG.6;

FIG. 8 is a front end perspective view from above the firing assembly ofthe surgical fastener applying apparatus shown in FIG. 3;

FIG. 9 is an enlarged view of the indicated area of detail shown in FIG.8;

FIG. 9A is a top, perspective view of the channel member with the firingassembly releasably secured therein;

FIG. 9B is an enlarged view of the indicated area of detail shown inFIG. 9A;

FIG. 9C is a top, perspective view of a central portion of the channelmember;

FIG. 10 is a rear end perspective view from above of the firing assemblyshown in FIG. 8;

FIG. 11 is an enlarged view of the indicated area of detail shown inFIG. 10;

FIG. 12 is a side perspective view of the firing assembly shown in FIG.10 with parts separated;

FIG. 12A is a bottom perspective view of the cam bar of the firingassembly shown in FIG. 12;

FIG. 12B is a bottom perspective view of the firing lever of the firingassembly shown in FIG. 12;

FIG. 13 is a side perspective view of the SULU of the surgical fastenerapplying apparatus shown in FIG. 1;

FIG. 14 is an enlarged view of the indicated area of detail shown inFIG. 13;

FIG. 15 is a front perspective view of the SULU shown in FIG. 13;

FIG. 16 is an enlarged view of the indicated area of detail shown inFIG. 15;

FIG. 17 is a side perspective view with parts separated of the SULUshown in FIG. 15;

FIG. 18 is a side cross-sectional view of the surgical fastener applyingapparatus shown in FIG. 1 in the open position;

FIG. 19 is an enlarged view of the indicated area of detail shown inFIG. 18;

FIG. 20 is an enlarged view of the indicated area of detail shown inFIG. 18;

FIG. 21 is a perspective view of the proximal end of the surgicalfastener applying apparatus shown in FIG. 18 in the open position;

FIG. 22 is an enlarged view of the indicated area of detail shown inFIG. 18;

FIG. 23 is a perspective view from below of the proximal end of theclamping lever of the surgical fastener applying apparatus shown in FIG.1;

FIG. 24 is a side perspective view of the surgical fastener applyingapparatus shown in FIG. 1 in the clamped position;

FIG. 25 is a side cross-sectional view of the surgical fastener applyingapparatus shown in FIG. 24 in the clamped position;

FIG. 26 is an enlarged view of the indicated area of detail shown inFIG. 25;

FIG. 27 is an enlarged view of the indicated area of detail shown inFIG. 25;

FIG. 28 is a cross-sectional view taken along section lines 28-28 ofFIG. 26;

FIG. 29 is a top view of the surgical fastener applying apparatus shownin FIG. 1 as the firing assembly is moved through an actuating stroke toeject fasteners from the fastener applying apparatus;

FIG. 30 is a side cross-sectional view of the surgical fastener applyingapparatus shown in FIG. 29 with the firing assembly in the actuatedposition;

FIG. 31 is an enlarged view of the indicated area of detail shown inFIG. 30;

FIG. 32 is an enlarged view of the indicated are of detail shown in FIG.30;

FIG. 33 is a side cross-sectional view of the surgical fastener applyingapparatus shown in FIG. 1 after the apparatus has been fired and movedto the open position;

FIG. 34 is an enlarged view of the indicated area of detail shown inFIG. 33;

FIG. 35 is a perspective view of an alternate embodiment of thestationary housing of the firing assembly prior to insertion of theSULU;

FIG. 35A is a side cross-sectional view of a center portion of thestationary housing of FIG. 35 shown in a position that preventsinsertion of the SULU therein;

FIG. 35B is a side cross-sectional view of a center portion of thestationary housing of FIG. 35 shown in a position that allows insertionof the SULU therein;

FIG. 36 is a schematic view of another alternate embodiment of thestationary housing of the firing assembly prior to insertion of the SULUtherein;

FIG. 36A is a side cross-sectional view of a center portion of thestationary housing of FIG. 36 shown in a position that prevents entry ofthe SULU therein; and

FIG. 36B is a side cross-sectional view of a center portion of thestationary housing of FIG. 36 shown in a position that allows entry ofthe SULU therein.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the presently disclosed surgical fastener applyingapparatus in accordance with the present disclosure will now bedescribed in detail with reference to the drawings wherein likereference numerals identify similar or identical structural elements. Asused herein, as is traditional, the term “proximal” refers to the end ofthe apparatus which is closer to the user and the term distal refers tothe end of the apparatus which is further away from the user.

FIGS. 1-34 illustrate one embodiment of the presently disclosed surgicalfastener applying apparatus designated generally as surgical stapler 10.Referring specifically to FIGS. 1-3, surgical stapler 10 includes ananvil half-section 12, a cartridge receiving half-section 14, a clampinglever 16, a single use loading unit 18 (hereinafter “SULU”) and a firingassembly 20. In one embodiment, anvil half-section 12, cartridgereceiving half-section 14 and clamping lever 16 are constructed to bereusable components and, as such, are constructed from a biocompatiblematerial suitable for sterilization and repeated use, e.g., stainlesssteel. In contrast, SULU 18 and firing assembly 20 are constructed to bedisposable and, as such, may be constructed from any suitablebiocompatible material, e.g., plastics, metals, combinations thereof,having the requisite strength characteristics.

Referring to FIGS. 3-7, cartridge receiving half-section 14 defines anelongated channel member 22 which defines a substantially U-shapedchannel 24 having a distal portion 24 a dimensioned to releasablyreceive a SULU 18 and a proximal portion 24 b dimensioned to releasablyreceive firing assembly 20. Firing assembly 20 includes a stationaryhousing 26 (see also FIG. 12) having a proximal end including openings28 which receive ends of pivot members 29 (FIG. 12). Pivot members 29pivotally support a locking member 206 on a proximal end of stationaryhousing 26 and extend through openings 28 into recesses 30 formed in aproximal portion of cartridge receiving half-section 14 to releasablysecure the proximal end of firing assembly 20 within the proximalportion 24 b of channel member 22 as will be discussed in further detailbelow. The distal end of firing assembly 20 defines a triangular cutout64 d. Cutout 64 d is positioned to receive a protrusion 65 formed on aninner wall of channel member 22 (see FIGS. 9A-9C) to releasably securethe distal end of firing assembly 20 within channel member 22. Thestructure of firing assembly 20 will also be discussed in further detailbelow. Likewise, SULU 18 includes a pair of distal protrusions 32 whichare positioned in cutouts 34 formed at the distal end of channel member22 to releasably secure SULU 18 within the distal portion 24 a ofchannel member 22. During assembly, firing assembly 20 must be insertedinto proximal portion 24 b of channel member 22 before SULU 18 isinserted into distal portion 24 a of channel member 22 as will bediscussed below. To position SULU 18 in channel member 22, protrusions32 on SULU 18 are positioned within cutouts 34 while SULU 18 ispositioned above and at an angle to channel member 22. Thereafter, SULU18 can be rotated downwardly into distal portion 24 a of U-shapedchannel 24. This allows for the drive components of firing assembly 20to properly align with components of SULU 18 and also facilitatesengagement of the firing assembly 20 with a knife 40 (FIG. 17) supportedwithin SULU 18. A proximal end of SULU 18 includes an outwardlyextending serrated surface 42 (FIG. 7) to facilitate gripping of theproximal end of SULU 18 to allow for removal and/or replacement of SULU18 from channel member 22. Prior to movement of stapler 10 to theclamped position, as will be discussed below, serrated gripping surface42 will not fully seat within distal portion 24 a of channel member 22.

Referring to FIGS. 8-12, firing assembly 20 includes stationary housing26, a knife actuating bar 44, a cam bar 46, a guide block 48, a firinglever 50, a slide block 52, a pedal 54 and the pivotal locking member206 (FIG. 12). In one embodiment, stationary housing 26 includes aU-shaped frame 60 including a bottom wall 62 and a pair of sidewalls 64.The distal end of each sidewall 64 defines a proximal step 64 b, adistal angled portion 64 c (FIG. 9) and the triangular cutout 64 d. Asdiscussed above, triangular cutout 64 d is positioned to receive theprotrusion 65 (FIG. 9B) formed on an inner wall of channel member 22. Aproximal end of each sidewall 64 includes a pair of transverselyextending deformable wall portions 66 (FIG. 11) which are spaced from aproximal end of slide block 52 and define an area between wall portions66 and slide block 52 for pivotally receiving locking member 206 as willbe discussed in further detail below.

Guide block 48 includes a body defining three longitudinal slots 70 a-cand a pair of outwardly extending protrusions 72. In one embodiment,each protrusion 72 is substantially cylindrical and includes a taperedportion 72 a (FIG. 9). Alternately, other protrusion configurations areenvisioned. Protrusions 72 are dimensioned to be received in openings 74(FIG. 12) formed in sidewalls 64 of stationary housing 26 to axially fixguide block 48 within the distal end of stationary housing 26.Protrusions 72 allow for a degree of pivotal movement of guide block 48within U-shaped frame 60. As will be discussed in further detail below,guide block 48 is pivotal from a first position (FIG. 19) in lockingengagement with notches 49 and 51 of knife actuating bar 44 to a secondposition (FIG. 26) disengaged from notches 49 and 51 of knife actuatingbar 44 in response to movement of stapler 10 to the clamped position. Atorsion spring is provided about protrusion 72 to urge guide block 48into locking engagement with notches 49 and 51. Each of slots 70 a and70 c is dimensioned to slidably receive a respective sidewall 114 of cambar 46. Similarly, slot 70 b is dimensioned to slidably receive knifeactuating bar 44.

Slide block 52 includes a hub 80 which includes a resilient finger 80 aconfigured to be snap-fit into a pivot hole 82 formed in firing lever50. Firing lever 50 is pivotal about hub 80 when the slide block 52 isin a retracted position to facilitate actuation of the firing assembly20 from either side of stapler 10. Pedal 54 is reciprocally receivedwithin a hole 84 formed in slide block 52. Pedal 54 includes a splitbody portion 54 a which is configured to straddle a proximal end 102 ofknife actuating bar 44. In one embodiment, split body portion 54 aincludes an angled distal surface 86. A pin 88 extends upwardly frompedal 54 through hole 84 in slide block 52. A biasing member 90 ispositioned between split body portion 54 a and slide block 52, about pin88 to urge pedal 54 downwardly away from slide block 52 to an extendedposition. In the retracted position of slide block 52, pedal 54 isreceived in a cutout 55 formed in a bottom wall 22 a of channel member22 (FIG. 20).

Firing lever 50 includes first and second finger engagement members 50 aand 50 b, either one of which can be selectively engaged to move thefiring lever 50 through a firing stroke from either side of stapler 10.An arcuate recess 94 (FIG. 12B) is formed in a bottom surface of firinglever 50 which slidably receives pin 88 of pedal 54 to define the rangeof rotation through which firing lever 50 can pivot about hub 80 ofslide block 52. As used herein, a firing stroke is defined as movementof firing lever 50 from a fully retracted position (FIG. 25) to a fullyadvanced position (FIG. 30). A stop recess 94 a is formed at each end ofarcuate recess 94. Stop recesses 94 a are configured and dimensioned toreceive the end of pin 88 of pedal 54 to prevent pivotal movement offiring lever 50 about hub 80 during a firing stroke of surgical stapler10. More specifically, when the firing assembly 20 is actuated toadvance slide block 52 distally within stationary housing 26, angleddistal surface 86 of pedal 54 engages channel member 22 and is cammedout of cutout 55 (FIG. 27) to urge pin 88 upwardly into a stop recess 94a to prevent pivotal movement of firing lever 50 during movement offiring lever 50 through a firing stroke. As is evident, pin 88 must bepositioned beneath a stop recess 94 a to allow pedal 54 to lift upwardlyfrom cutout 55 to allow firing lever 50 to be moved through the firingstroke. Thus, firing lever 50 must be pivoted to one side or the otherof firing assembly 20 before the firing lever 50 can be moved through afiring stroke.

Knife actuating bar 44 includes a proximal end having a stepped portion100 which includes a proximal first step 102 having a first height and asecond step 104 having a second height which is greater than the firstheight. A distal end of actuating bar 44 includes an upturned hookportion 106 and upper and lower notches 49 and 51. A finger 108 projectsupwardly from knife actuating bar 44 between first and second steps 102and 104. As shown in FIG. 27, finger 108 is slidably received within arecess 110 formed in an underside of slide block 52. When slide block 52is advanced distally within stationary housing 26, finger 108 moveswithin recess 110 such that slide block 52 moves in relation to knifeactuating bar 44 until finger 108 engages a wall 112 (FIG. 32) defininga proximal end of recess 110. When finger 108 engages wall 112, furtherdistal movement of slide block 52 will also effect distal movement ofknife actuating bar 44. As will be evident below, this arrangementallows for staples to be ejected from SULU 18 prior to cutting oftissue.

Referring to FIGS. 12 and 12A, cam bar 46 includes a pair of sidewalls114 and a base wall 116 (FIG. 12A). The proximal end 114 a of eachsidewall 114 includes a raised wall portion 118. Each raised wallportion 118 is configured to be fixedly received in a slot (not shown)formed in an underside of slide block 52 to fixedly secure the proximalend of cam bar 46 to slide block 52. Alternately, slide block 52 may bemolded about the proximal end of knife actuating bar 44. The distal endof each sidewall 114 includes an angled camming surface 114 b. Base wall116 defines a distally extending elongated slot 123 (FIG. 12A) whichextends from the distal end of cam bar 46 along a substantial length ofthe cam bar 46 and a proximally extending longitudinal slot 121. Slot121 is positioned to facilitate the passage of pedal 54 through cutout55 of channel member 22 when slide block 52 is in the retractedposition. See FIG. 27.

Sidewalls 114 of cam bar 46 are slidably positioned in slots 70 a and 70c of guide block 48 and knife actuating bar 44 is slidably positioned inlongitudinal slot 70 b of guide block 48. When firing assembly 20 issupported in channel member 22 and firing lever 50 is pivoted to oneside of stationary housing 26 and pushed distally, slide block 52 ismoved distally within stationary housing 26. As slide block 52 begins tomove distally, tapered surface 86 of pedal 54 engages a proximal edge ofchannel member 22 defining cutout 55 to urge pedal 54 upwardly out ofcutout 55, through slot 121 of cam bar 46, and onto an inner surface ofstationary housing 26 of firing assembly 20 (FIG. 27). As this occurs,pin 88 of pedal 54 moves into a stop recess 94 a to prevent furtherpivotal movement of firing lever 50. If firing lever 50 is not pivotedto a position in which pin 88 is positioned beneath a stop recess 94 a,pedal 54 will be prevented from moving upwardly out of cutout 55 andfiring lever 50 will be prevented from moving through a firing stroke.As firing lever 50 is moved distally, finger 108 moves within recess 110such that knife actuating bar 44 remains stationary as cam bar 46 isadvanced distally. When finger 108 engages proximal wall 112 definingrecess 110, knife actuating bar 44 is moved distally with slide block 52and cam bar 46. As will be discussed below, when cam bar 46 and knifeactuating bar 44 are moved distally within stationary housing 26 offiring assembly 20 and channel member 22, angled camming surfaces 114 bof cam bar 46 are moved through SULU 18 to eject fasteners from SULU 18.Simultaneously, although with a preset delay equal to the length ofrecess 110 (FIG. 32), knife actuating bar 44 drives a knife blade 40through SULU 18 to dissect tissue.

U.S. Pat. No. 7,631,794 (“the '794 patent”) discloses a surgicalfastener applying apparatus which includes a firing assembly similar tothat described above. The '794 patent is incorporated herein byreference in its entirety.

FIGS. 13-17 illustrate SULU 18. Referring to FIG. 17, SULU 18 includes abody 120, a plurality of staple pushers 122 (only one is shown), abottom cover 124, a knife 40 having an angled sharpened leading edge orblade 40 a, a plurality of staples 126 (only one is shown), and apivotally mounted safety lockout 128. A proximal end of body 120includes a flexible finger 120 a which projects slightly beyond theouter wall defining body 120. Finger 120 a frictionally engages an innerwall of channel member 22 to retain the proximal end of SULU 18 withinchannel member 22 when SULU 18 is releasably positioned within channelmember 22. As is known in the art, body 120 has a plurality of rows ofstaple retaining slots 130, e.g., four, six, etc. and a linear slottedknife track 132 centrally disposed in body 120. Surgical stapler 10 canbe dimensioned to receive or accommodate SULU's of different staple linelengths including, e.g., 60 mm, 80 mm and 100 mm. Knife 40 includes adownturned hook portion 40 b which is positioned to engage upturned hookportion 106 (FIG. 12) of knife actuating bar 44 when SULU 18 ispositioned within channel member 22.

In the illustrated embodiment, body 120 includes two staggered rows ofslots 130 formed on either side of linear slotted knife track 132. Thestaggered rows of slots 130 extend beyond the distal end of knife track132 to facilitate staple formation beyond the distal end of the strokeof the knife blade 40.

Staple pushers 122 may be configured to extend into one or more slots130. In one embodiment, a single pusher is associated with each slot130. Alternately, as illustrated in FIG. 17, each pusher 122 can beconfigured to extend into two adjacent slots 130 and is positionedbeneath respective staples 126 which are retained in slots 130. As isknown in the art, each pusher 122 includes a lower cam surface 122 awhich is positioned to engage one of cam surfaces 114 b (FIG. 12) on thedistal end of cam bar 46 such that movement of cam bar 46 through SULU18 sequentially lifts each respective pusher 122 within its respectiveslot or slots 130 to eject staples from slots 130.

Bottom cover 124 partially encloses a channel 125 (FIG. 18) formedwithin the cartridge body 120. A longitudinal ridge 134 is formed on anupper surface of bottom cover 124 and provides a bearing surface for aknife supporting member 136 which is secured to a bottom edge of knife40. Knife 40 may be secured to supporting member 136 via pins, weldingor other known fastening techniques. During a firing stroke, knife 40 isguided along knife track 132 as the firing lever 50 is advanced throughchannel member 22. A pair of slots 138 is defined between the sides ofridge 134 and an outer wall of cartridge body 120. Longitudinal ridge134 is positioned within body 120 and dimensioned to be slidablyreceived in elongated slot 120 (FIG. 12A) of cam bar 46 such that cambar 46 is slidably movable through cartridge body 120 about longitudinalridge 134 to eject staples 126 from SULU 18.

Safety lockout 128 is pivotally disposed on an upper proximal end ofbody 120 and is pivotal about a pivot member 150 from a lockedorientation (FIG. 26) to unlocked orientation (FIG. 34). Pivot member150 is received in openings 154 in body 120. A biasing member, e.g.,spring 152, is positioned between knife supporting member 136 and safetylockout 128 to urge safety lockout 128 towards the unlocked orientation.Safety lockout 128 includes a proximal hook 156 which is positioned toreceive an engagement member 158 formed on the knife 40 to retain thesafety lockout 128 in the locked orientation when the knife 40 is in theretracted position (FIG. 19). When the knife 40 is moved towards theadvanced position during a firing stroke, engagement member 158 is movedaway from proximal hook 156 to allow safety lockout 128 to pivot towardsthe unlocked position in response to the urging of spring 152. It isnoted that safety lockout 128 is prevented from pivoting to the unlockedposition when the anvil half-section 12 and cartridge receivinghalf-section 14 are in the clamped position because the top surface 128a of safety lockout 128 engages an inner surface of anvil half-section12 to prevent pivoting of safety lockout 128. Safety lockout 128 definesa slot 160 dimensioned to slidably receive the knife 40. In theretracted position of the knife 40, the leading edge 40 a of knife 40 isconfined within slot 160 safety lockout 128 to prevent accidentalengagement and injury to medical personnel with leading edge 40 a ofknife 40.

Referring again to FIGS. 2-3, anvil half-section 12 includes a proximalhandle portion 12 a and a distal anvil portion 12 b. Anvil portion 12 bincludes a staple deforming portion 198 which, as known in the art,includes a plurality of staple deforming recesses and faces a topsurface of SULU 18 when SULU 18 is positioned in the channel member 22.As is also known in the art, the staple deforming portion 198 includes acentral longitudinal slot (not shown) for receiving the knife 40 (FIG.17) as the knife 40 is moved through the SULU 18. The staple deformingportion 198 can be formed integrally with anvil half-section 12, or inthe alternative, secured to anvil half-section 12 by a fastening processsuch as welding. A pair of locating fingers 170 (FIG. 3) are positionedadjacent the proximal end of the staple deforming portion 198 of anvilportion 12 b. Locating fingers 170 are received in grooves in SULU 18 toproperly align SULU 18 with staple determining portion 198 when theapparatus is in a clamped position.

A central portion of anvil half-section 12 includes a pair ofcylindrical lateral support members 172. During assembly of anvilhalf-section 12 and cartridge receiving half-section 14, lateral supportmembers 172 are supported in U-shaped recesses 174 defined in a centralportion 173 of cartridge receiving half-section 14 (FIG. 28). A distalwall 173 a of central portion 173 defines a tissue stop (FIG. 3).Lateral support members 172 are also positioned to be received incutouts 176 formed on spaced flange portions 178 of clamping lever 16when the clamping lever 16 is moved to the clamped position (FIG. 2B).Proximal handle portion 12 a is ergonomically formed and includes athumb-engaging abutment 180 and a gripping portion 182. A proximal endof handle portion 12 a includes a downwardly extending finger 184 whichincludes a pair of opposed teardrop shaped protrusions 186 which will bediscussed in further detail below. Alternately, protrusions 186 mayassume a variety of configurations.

Cartridge receiving half-section 14 includes spaced centrally disposedU-shaped recesses 174 positioned to support lateral support members 172of anvil half-section 12. The proximal end of cartridge receivinghalf-section 14 includes a pair of vertical support members 188. Eachvertical support member 188 includes an elongated vertical slot 188 ahaving a rounded bottom surface. Vertical slots 188 a are dimensioned toreceive protrusions 186 formed on finger 184 of anvil half-section 12(FIG. 21) when the anvil half-section 12 is supported on the cartridgereceiving half-section 14 during assembly. By positioning protrusion 186within the vertical slots 188 a, anvil half-section 12 can be pivoted ina scissor-like manner with respect to the cartridge receivinghalf-section 14 between open and closed positions. In one embodiment,protrusions 186 have a teardrop profile. At least one sidewall ofcartridge receiving half-section 14 includes a depression 189 (see FIG.3) which will be discussed in further detail below.

Clamping lever 16 also includes a handle portion 190 including a grip190 a and a thumb engaging abutment 192. As discussed above, a pair ofspaced flange portions 178 is supported on the distal end of clampinglever 16. Each flange portion 178 defines a cutout 176 dimensioned toreceive a respective lateral support member 172 of anvil half-section 12when stapler 10 is moved towards clamped position (FIG. 2B). The distalend of clamping lever 16 also defines a pair of openings 194 which aredimensioned to receive a pivot member 187. Pivot member 187 isdimensioned to extend through openings 195 in cartridge receivinghalf-section 14 and openings 194 in clamp lever 16 to pivotally secureclamp lever 16 to cartridge receiving half-section 14.

As shown in FIG. 3A, an inner wall of clamping lever 16 includes aprotrusion 201. Protrusion 201 is positioned within depression 189 (FIG.2A) formed in the sidewall of cartridge receiving half-section 14 toreleasably retain clamp lever 16 in the unclamped position or openposition (FIG. 2A).

In order to load firing assembly 20 into proximal portion 24 b ofchannel member 22, the stationary housing 26 of firing assembly 20 isslid into the channel member 22 through the proximal end of channelmember 22 until pivot members 29 are received in recesses 30 formed inthe proximal end of channel member 22. After firing assembly 20 isloaded, the SULU 18 can be loaded into distal portion 24 a in the mannerdiscussed above.

Referring to FIGS. 2 and 2B, after SULU 18 and firing assembly 20 areloaded into channel member 22, anvil section 12 can be assembled tocartridge receiving half-section 14. To attach anvil half-section 12 tocartridge receiving half-section 14, protrusions 186 of fingers 184 arepositioned in vertical slots 188 a of vertical support member 188 ofcartridge receiving half-section 14. Thereafter, anvil half-section 12is rotated towards cartridge receiving half-section 14 to positionlateral supports members 172 in U-shaped recesses 174.

In order to position surgical stapler 10 in the clamped position,clamping lever 16 is rotated in a counter-clockwise direction from theposition shown in FIG. 2A. As clamping lever 16 is rotated, lateralsupport members 172 are received in cutouts 176 (FIG. 2) of flangeportions 178 and cammed towards cartridge receiving half-section 14. Asshown in FIG. 3, a spring member 200 is secured to an inner surface ofclamping lever 16, such as by welding, at a position to engage cartridgereceiving portion 14 to urge clamping lever 16 to the non-clampedposition shown in FIG. 2A. In the clamped position shown in FIG. 1, thestaple deforming portion 198 is positioned in close approximation withthe top surface of SULU 18.

Referring to FIGS. 3, 3A and 12, as discussed above, a pivotal lockingmember 206 is pivotally supported on the proximal end of stationaryhousing 26 of firing assembly 20. Pivotal locking member 206 includespivot members 29 which extend through openings 28 defined in stationaryhousing 26. A finger engagement member 212 is positioned on one end oflocking member 206 and a latch portion 210 is positioned on the otherend of locking member 206. Latch portion 206 includes a hook member 210a. A biasing member 214 is positioned about a pivot member 29 to urgelatch portion 210 inwardly towards stationary housing 26 of firingassembly 20. When locking member 206 is secured on firing assembly 26,latch portion 210 extends downwardly through an opening 216 in aproximal end of stationary housing 26 to a position below a bottomsurface of channel member 22 (FIG. 20). As discussed above, the ends ofpivot members 29 are received in cutouts 30 formed in the proximal endof cartridge receiving half-section 14 to releasably secure firingassembly 20 within proximal channel portion 24 b of channel member 22(FIG. 21). Cutouts 30 are partially defined by downturned fingers 220 toretain firing assembly 26 within channel member 22 (FIG. 3).

Referring to FIG. 3A, a proximal end of clamping lever 16 includes anengagement member, e.g., cylindrical post 218, which is positioned to beengaged by hook member 210 a of latch portion 210 when the clamp lever16 is moved to the clamped position (FIG. 27). Although a post isillustrated, other engagement member configurations are envisioned. Ascan be seen by viewing FIG. 27, as clamping lever 16 is moved towardsthe clamped position, an angled face 222 of latch portion 210 engagespost 218. This engagement causes locking member 206 to pivot about pivotmembers 29 such that hook member 210 a of latch portion 210 passes byand then snaps into engagement with post 218. To release latch portion210 from post 218, engagement member 212 of locking member 206 isdepressed to pivot latch portion 210 out of engagement with post 218.When this occurs, spring member 200 urges clamping lever 16 to theunclamped position.

Referring to FIGS. 3, 12, 19 and 26, as discussed above, guide block 48is pivotally supported in stationary housing 26 of firing assembly 20.Guide block 48 includes a distally extending nose portion 220 (FIGS. 12and 26) which rests beneath SULU 18 when SULU 18 is supported in channelmember 22. The internal surface of guide block 48 includes lockingsurfaces 222 (FIG. 19) which are received in notches 49 and 51 of knifeactuating bar 44 when the stapler 10 is in an unclamped position. Whenthe SULU 18 is positioned in the channel member 22, prior to movingclamp lever 16 to the clamped position, SULU 18 is positioned atop noseportion 220 and is not fully seated in the channel member 22, asdiscussed above. When the stapler 10 is moved to the clamped position,locating fingers 170 (FIG. 3) engage a top surface of body 120 of SULU18 to fully seat SULU 18 in channel member 22. As discussed above,locating fingers 170 are received in grooves in SULU 18 to properlyposition SULU 18 in relation to anvil portion 12 b. As SULU 18 is fullyseated in channel member 22, SULU 18 presses downwardly on nose portion220 of guide block 48 to pivot guide block 48 about protrusions 72. Whenguide block 48 pivots, locking surfaces 222 move from notches 49 and 51to unlock knife actuating bar 44 (FIG. 26). This configuration preventsmovement of the knife actuating bar 44 in relation to guide block 48prior to clamping to ensure that the knife actuating bar 44 and SULUknife 40 remain properly positioned for operational engagement prior touse.

Referring to FIGS. 24-28, when stapler 10 is in the clamped, unfiredposition, slide block 52 of firing assembly 20 is in the retractedposition at the proximal end of channel member 22 and stationary housing26. See FIG. 27. In this position, pedal 54 is positioned in cutout 55of channel member 22 and pin 88 of pedal 54 is positioned in arcuaterecess 94 of firing lever 50 beneath stop recesses 94 a. As such, firinglever 50 can be pivoted to facilitate actuation of stapler 10 fromeither side of the stapler 10. In addition, in this position of slideblock 52, finger 108 of knife actuating bar 44 is positioned adjacentthe distal wall of recess 110 of slide block 52. Latch portion 210 oflocking member 206 is also engaged with post 218 to retain clampinglever 16 in the clamped position.

Referring to FIG. 26, when slide block 52 is in the retracted position,knife 40 and cam surfaces 114 b of cam bar 46 are positioned in theproximal end of SULU 18 and, proximal hook 156 of safety lockout 128 ispositioned in engagement with engagement member 158 of knife 40 toretain safety lockout 128 in the locked orientation. In addition,downturned hook portion 40 b of knife 40 is engaged with upturned hookportion 106 of knife actuating bar 44 to connect firing assembly 20 toknife 40 of SULU 18.

Referring to FIGS. 29-32, when the firing lever 50 is advanced distallyin the direction indicated by arrow “A” in FIG. 29, slide block 52 ismoved distally within stationary housing 26 of firing assembly 20 toeffect corresponding movement of cam bar 46 and delayed movement ofknife actuating bar 44. As discussed above, the delayed movement of theknife actuating bar 44 is equal to the length of recess 110 of slideblock 52 and results from movement of finger 108 of knife actuating bar44 within recess 110 of slide block 52. Movement of knife actuating bar44 with slide block 52 begins when finger 108 abuts the proximal wall112 of recess 110. As cam bar 46 is moved distally through stationaryhousing 26 of firing assembly 20, cam surfaces 114 b on sidewalls 114 ofcam bar 46 are advanced through SULU 18 to sequentially engage pushers122 to eject staples 126 from slots 130 of body 120. Concurrently, sincethe distal end of knife actuating bar 44 is engaged with knife 40, knife40, after the preset delay, is advanced through SULU 18 to incise tissuebetween the staple lines.

As shown in phantom in FIG. 32, when slide block 52 moves distallywithin stationary housing 26, pedal 54 rides up over channel member 22and moves along inner surface of stationary housing 26 of firingassembly 20. When this occurs, pin 88 of pedal 54 moves into a stoprecess 94 a to prevent further pivotal movement of firing lever 50.

Referring to FIGS. 31 and 32, when knife 40 is moved distally withinSULU 18, engagement member 158 of knife 40 is disengaged with proximalhook 156 of safety lockout 128.

Referring to FIGS. 33 and 34, when the firing lever 50 is returned toits proximal-most position to retract cam bar 46 and knife 40, and thelocking member 206 is depressed to disengage latch portion 210 from post218, spring 200 urges clamping lever 16 to its unclamped position toallow stapler 10 to move to the open position. In the open position,anvil half-section 12 is spaced from cartridge receiving half-section 14and spring 152 (FIG. 17) pivots safety lockout 128 in the directionindicated by arrow B in FIG. 34 about pivot member 150 to its unlockedposition such that safety lockout 128 projects upwardly from SULU 18. Inthe unlocked position, safety lockout 128 prevents movement of thestapler 10 back to the clamped position. In order to reuse stapler 10,used SULU 18 must be replaced with a new SULU 18.

During a surgical procedure, SULU 18 can be replaced multiple times tofacilitate multiple uses of stapler 10 on a single patient. Since eachSULU 18 is provided with a fresh knife 40, tearing of tissue isminimized. After the surgical procedure, the used SULU(S) 18 and thefiring assembly 20 can be removed from the channel member 22 anddisposed of in an appropriate manner. The anvil half-section 12,cartridge receiving half-section 14 and clamping lever 16 can now besterilized, such as by autoclaving, and reused with a sterilized SULU 18and firing assembly 20 in the manner discussed above. Because thelocking member 206 forms part of the firing assembly 20 and isdisposable, fewer areas remain on the reusable components for tissue andfluids to become trapped. As such, the reusable components of theapparatus can be more easily sterilized.

In the surgical stapler described above, the SULU 18 and the firingassembly 20 are independently secured to and independently removed fromthe channel member 22 of the cartridge receiving half-section 14. Inalternative embodiments illustrated in FIGS. 35-36B, the SULU 18 and thefiring assembly 20 are configured to form a single disposable unit, andthe cartridge receiving half-section is configured to receive the singledisposable unit. In particular, the stationary housing of the firingassembly is configured to support both the SULU and the firingcomponents of the surgical stapler 10, e.g., knife actuating bar, cambar, guide block, and slide block shown in FIGS. 8-12. When thestationary housing is inserted into the channel member 22 of thecartridge receiving half-section, the SULU and the firing components areconcurrently mounted to the cartridge receiving half-section. Thestationary housing includes a lockout structure to prevent insertion ofthe SULU into the stationary housing after the stationary housing hasbeen inserted into the cartridge receiving half-section. Thus, in theseembodiments, the SULU must be inserted into the stationary housingbefore inserting the stationary housing into the cartridge receivinghalf-section. Specific embodiments of the stationary housing arediscussed below.

FIG. 35 schematically illustrates an alternate embodiment of thestationary housing 326 associated with the firing assembly 320. Thestationary housing 326 can define a length substantially similar to thatof the cartridge receiving half-section 14 (FIG. 3). The stationaryhousing 326 is configured to be releasably received within the channelmember 22 (see also FIG. 3) of the cartridge receiving half-section 14.The stationary housing 326 includes a proximal portion 330, a distalportion 332 and a center portion 340 therebetween.

The proximal portion 330 of the stationary housing 326 is configured tosupport the firing components of the surgical stapler 10 shown in FIGS.8-12 in the same manner as stationary housing 26, such firing componentsincluding the knife actuating bar, cam bar, guide block, and slide block(not shown in FIG. 35).

The distal portion 332 and the center portion 340 of the stationaryhousing 326 together are of a length substantially similar to that ofthe SULU (single use loading unit) 318, and together are configured toreleasably receive the SULU 318. The stationary housing 326 has a firstposition which prevents full operable insertion of the SULU 318 into thedistal portion 332 and the center portion 340 of the stationary housing326, and a second position which permits full operable insertion of theSULU 318 into the distal portion 332 and the center portion 340 of thestationary housing 326.

The distal portion 332 of the stationary housing 326 has a U-shapedframe 360 including a bottom wall 362 and a pair of sidewalls 364. Theproximal portion 330 may have an identical or similar structure as thatof the distal portion 332. The center portion 340, on the other hand,does not have a bottom wall, but rather has a pair of sidewalls 342 thatare hingedly attached to the proximal portion 330 and the distal portion332 via live hinges 334, which are flexible and resilient. Each sidewall342 of the center portion 340 is pivotable about the live hinges 334.

As illustrated in FIGS. 35-35A, when the stationary housing 326 is inthe first position, the sidewalls 342 of the center portion 340 arecorrespondingly in their first, unbiased position in which the sidewalls342 are in substantially parallel relation with respect to each other,and the sidewalls 342 are substantially aligned with respect to thesidewalls 364 of the distal portion 332. By contrast, when thestationary housing 326 is in the second position, the sidewalls 342 ofthe center portion 340 are correspondingly in their second, inclinedposition as shown in FIG. 35B in which the sidewalls 342 are inclinedaway from each other. In the absence of any external force or pressure,the sidewalls 342 naturally assume their first position, and for thesame reason, the stationary housing 326 naturally assumes its firstposition. Application of force pivots or flexes the sidewalls 342 aboutthe live hinges 334 due to the flexible nature of the live hinges 334,moving the sidewalls 342 from the first position to the second, inclinedposition, correspondingly moving the stationary housing 326 from itsfirst position to its second position. Upon removal of the force, thesidewalls 342 resume their first position owing to the resilient natureof the live hinges 334, and simultaneously returning the stationaryhousing 326 to its first position.

It is also contemplated in an alternate embodiment that the sidewallsare formed such that they require manual application of force to pivotbetween both first and second positions. Alternatively, the sidewalls342 can be biased to the non-blocking position with the sidewalls of thecartridge receiving half sections moving sidewalls 342 to the blockingposition.

Each sidewall 342 includes a downwardly extending portion 346 which canextend beyond the bottom surface 362 of the distal portion 332, andserves as a manual member to facilitate manual manipulation of thesidewalls 342. In one embodiment, the downwardly extending portions 346each have a semi-circular configuration. Alternatively, otherconfigurations are contemplated. An inward pressure upon the pair ofdownwardly extending portions 346 toward the longitudinal axis of thestationary housing 326, e.g. by the user's fingers, effects pivotalmovement of the sidewalls 342 from the first, unbiased position to thesecond, inclined position. The sidewalls 342 return back to the first,unbiased position upon release of the inward pressure. The downwardlyextending portions 346 may further include a plurality of ridges 348protruding outwardly therefrom to facilitate frictional engagementbetween the user's fingers and the downwardly extending portions 346during manual manipulation.

Each sidewall 342 has a top flange 344 extending radially inwardly fromthe top thereof, defining an opening (gap) therebetween. When thesidewalls 342 of the center portion 340 are in their first position asillustrated in FIG. 35A, the two top flanges 344 are in a substantiallycoplanar configuration, and define a lateral dimension or opening “W1”therebetween which is less than the lateral dimension “W2” of the SULU318, thereby preventing entry of the SULU 318 into the stationaryhousing 326. When the sidewalls 342 of the center portion 340 are movedto their second, inclined position as illustrated in FIG. 35B, by inwardpressure on portions 346, the two flanges 344 move apart in thedirection as indicated by “B” in FIG. 35B creating an enlarged lateraldimension “W3” which is greater than the lateral dimension or opening(gap) “W2” of the SULU 318, thereby allowing entry of the SULU 318 intothe stationary housing 326.

Accordingly, when the sidewalls 342 are in their first position, the topflanges 344 prevent full insertion of the SULU 318 to an operableposition in the stationary housing 326. When the sidewalls 342 are intheir second, inclined position, the top flanges 344 are spaced apart topermit full insertion of the SULU 318 into the stationary housing 326 toan operable position cooperating with the pusher assembly so the staplescontained in the SULU 318 can be fired. After the SULU 318 is positionedinto the stationary housing 326, pressure on portions 346 is released,enabling the sidewalls 342 to return to their first position to preventremoval of the SULU 318 from the stationary housing 326. When the SULU318 is securely held within the stationary housing 326, the stationaryhousing 326 simultaneously supports the SULU 318 as well as the firingcomponents of the surgical stapler 10. As a result, the stationaryhousing 326, the SULU 138, and the firing components of the surgicalstapler 10 together form a single disposable unit.

During operation, a user first squeezes the downwardly extendingportions 346 of the stationary housing 326 towards each other to adjustthe sidewalls 342 of the center portion 340 to their second, inclinedposition, moving the stationary housing 326 to its second position toreadily accept a SULU 318 therein. Next, the user positions the SULU 318within the center portion 340 and the distal portion 332 of thestationary housing 326. After the SULU 318 is successfully positionedwithin the stationary housing 326, the user releases the semi-circularportions 346, causing the sidewalls 342 to return to their first normalposition, and simultaneously moving the stationary housing 326 to itsfirst position. Once the stationary housing 326 resumes its firstposition, the stationary housing 326 securely holds the SULU 318therein. With the firing components already loaded in the proximalportion 330 of the stationary housing 326, thereby forming a pusherassembly, and the SULU 318 loaded in the center portion 340 and thedistal portion 332 of the stationary housing 326, the firing components,the SULU 318 and the stationary housing 326 together form a singledisposable loading unit. The user then mounts the single disposable unitinto the cartridge receiving half-section by placing the stationaryhousing 326 into the channel member of the cartridge receivinghalf-section.

If the user mounts the stationary housing 326 into the cartridgereceiving half-section without first inserting the SULU 318 into thestationary housing 326, the walls of the cartridge receivinghalf-section confines the sidewalls 342 of the center portion 340 totheir first position, thereby forming a locking or blocking structurepreventing or blocking subsequent entry of the SULU 318 into thestationary housing 326. That is, the sidewalls 342 do not havesufficient space to be inclined to widen the opening therebetween asthere movement is obstructed. In that case, the stationary housing 326must be removed from the cartridge receiving half-section to thenincline the sidewalls 342 to allow the SULU 318 to be positioned in thestationary housing 326. Consequently, the SULU 318 needs to be insertedinto the stationary housing 326 prior to insertion of the stationaryhousing 326 into the stapler.

FIGS. 36-36B illustrate another alternate embodiment of the stationaryhousing 426 of firming assembly 420. The stationary housing 426 includesa proximal portion 430, a distal portion 432 and a center portion 440therebetween. The proximal portion 430 and the distal portion 432 havestructures and functions similar to that of the proximal and distalportions 330, 332, of stationary housing 326, respectively, as describedabove.

The center portion 440 defines a U-shaped configuration, including apair of sidewalls 442, a pair of flanges 444 each extendingsubstantially perpendicular from its associated sidewall 442 (toward alongitudinal axis of the stationary housing 426), and a bottom surface446. The bottom surface 446 is permanently attached to or alternativelyintegrally formed with the bottom surface 462 of the distal portion 432and the bottom surface 461 of the proximal portion 430. Each sidewall442 is hingedly attached to the bottom surface 446, and pivotable withrespect to the bottom surface 446.

Similar to the stationary housing 326, the stationary housing 426 alsohas a first position illustrated in FIG. 36A which prevents or blocksentry of the SULU 418 therein, and a second position illustrated in FIG.36B which permits entry of the SULU 418 therein. In some embodiments,the first position can be the normal biased position.

When the stationary housing 426 is in its first position illustrated inFIG. 36A, the pair of sidewalls 442 is correspondingly in a firstposition in which each sidewall 442 is substantially perpendicular tothe bottom surface 446, and the top flanges 444 are substantiallycoplanar with respect to each other and define a lateral dimension oropening (gap) “W1” smaller than the lateral dimension “W2” of the SULU418, thereby forming a lockout structure preventing insertion of theSULU 418 into the stationary housing 426.

When the stationary housing 426 is in its second position illustrated inFIG. 36B, the pair of sidewalls 442 is correspondingly in a secondposition in which the sidewalls 442 are inclined away from each other.Each sidewall 442 now defines an obtuse angle, e.g. “θ”, with respect tothe bottom surface 446. In this position, the top flanges 444 have alateral dimension “W3” therebetween, which is greater than the lateraldimension or opening (gap) “W2” of the SULU 418, thereby permittingentry of the SULU 418 into the stationary housing 426 into an operableposition to cooperate with the pusher assembly so the staples containedin the SULU 418 can be fired. Note SULU 418 (and SULU 318) can beidentical to SULU 18.

During operation, the user may first pivot each sidewall 442 outwardlyto adjust them to the second position as shown in FIG. 36B. The userthen places the SULU 418 into the center portion 440 and the distalportion 432 of the stationary housing 462. Next, the user releases (orpivots the sidewalls back to the first position in embodiments where thesidewalls are not biased to the first position) each sidewall 442 toenable it to return inwardly to the first position as shown in FIG. 36A,securing the SULU 418 within the stationary housing 426. At that time,the SULU 418, the stationary housing 426, and the firing componentscarried by the stationary housing 426 together form a single disposableunit. The user then mounts the single disposable unit into the cartridgereceiving half-section 14 (FIG. 3) by placing the stationary housing 426into the channel member (FIG. 3) of the cartridge receiving half-section14. If the user mounts the stationary housing 426 into the cartridgereceiving half-section without first inserting the SULU 418 into thestationary housing 426, the cartridge receiving half-section wouldconfine the sidewalls 442 of the center portion 440 of the stationaryhousing 426 to their first position, thus forming a locking structurepreventing or blocking subsequent insertion of the SULU 418 into thestationary housing 426. That is, the sidewalls 442 are obstructed by thesidewalls of the cartridge receiving half section so they do not havesufficient space to be pivoted or inclined, thus blocking entry of SULU418 therebetween.

Note that the sidewalls 442 can be formed to normally be in the firstposition. The sidewalls can alternatively be formed to normally be inthe non-blocking position and are moved to the blocking position byengagement with the sidewalls of the cartridge receiving half section.In other alternate embodiments, the sidewalls 442 can be formed suchthat the sidewalls 442 require manual application of force to pivotbetween both first and second positions.

As can be appreciated, FIGS. 35-36B illustrate different embodiments oflockout structure that can be used to prevent insertion of the SULU intothe stationary housing 326 or 426 if the stationary housing is mountedto the cartridge receiving half-section prior to the insertion of theSULU into the stationary housing. In preferred embodiments, the SULU andrespective stationary housing 326, 426 are disposable and the cartridgeand anvil receiving sections are reusable.

The SULU and stationary housing 326 or 426 can together be consideredthe firing assembly (320 and 420 of FIGS. 35 and 36, respectively), withthe stationary housing containing the pusher assembly to advance (fire)staples from the SULU.

It will be understood that various modifications may be made to theembodiments of the surgical fastener applying apparatus disclosedherein. Therefore, the above description should not be construed aslimiting, but merely as exemplifications of embodiments. Those skilledin the art will envision other modifications within the scope and spiritof the present disclosure.

1. A surgical fastener applying apparatus comprising: an anvilhalf-section including a distal anvil portion and a proximal handleportion; a cartridge receiving half-section defining an elongatedchannel member; a stationary housing configured to be releasablysupported within the elongated channel member of the cartridge receivinghalf-section, the stationary housing supporting firing components of theapparatus, the stationary housing dimensioned to releasably receive asingle use loading unit, the stationary housing including a lockoutstructure that prevents full insertion of the single use loading unitinto the stationary housing after the stationary housing is mounted inthe cartridge receiving half-section.
 2. The surgical fastener applyingapparatus according to claim 1, wherein the lockout structure is movablebetween a first position which prevents insertion of the single useloading unit into the stationary housing and a second position whichallows insertion of the single use loading unit into the stationaryhousing, wherein the lockout structure is obstructed from moving fromthe first position to the second position when the stationary housing issupported within the elongated channel member.
 3. The surgical fastenerapplying apparatus according to claim 2, wherein the lockout structureincludes a pair of sidewalls and a pair of flanges extending from thetop of each sidewall.
 4. The surgical fastener applying apparatusaccording to claim 3, wherein when the lockout structure is in the firstposition, the sidewalls are substantially parallel with respect to eachother, and the flanges define a first lateral dimension therebetweenwhich is less than a lateral dimension of the single use loading unit.5. The surgical fastener applying apparatus according to claim 3,wherein when the lockout structure is in the second position, thesidewalls are inclined away from each other, and the flanges define asecond lateral dimension therebetween which is larger than the lateraldimension of the single use loading unit.
 6. The surgical fastenerapplying apparatus according to claim 3, wherein the sidewalls of thecentral portion are connected to proximal and distal portions of thestationary housing by live hinges, such that the sidewalls of thecentral portion are pivotable with respect to the proximal and distalportions.
 7. The surgical fastener applying apparatus according to claim3, wherein the lockout structure includes a bottom surface, and thesidewalls are hingedly attached to the bottom surface.
 8. The surgicalfastener applying apparatus according to claim 1, wherein the stationaryhousing, the firing components, and the single use loading unit form asingle disposable unit when the single use loading unit is positionedwithin the stationary housing.
 9. The surgical fastener applyingapparatus according to claim 1, wherein the firing components include aknife actuating bar, cam bar, guide block and slide block.
 10. Thesurgical fastener applying apparatus according to claim 2, wherein thelockout structure is positioned on a central portion of the stationaryhousing.
 11. The surgical fastener applying apparatus according to claim2, wherein the lockout structure is normally in the first position. 12.A surgical fastener applying apparatus comprising a reusable anvilhalf-section, a reusable cartridge receiving half-section, and adisposable firing assembly configured to be releasably supported withinthe cartridge receiving half section, the firing assembly including adisposable pusher assembly and a single use loading unit operablymountable to the pusher assembly, wherein the single use loading unit isnot operably mountable to the pusher assembly if the pusher assembly ismounted in the cartridge receiving half section.
 13. The surgicalfastener applying apparatus according to claim 12, further comprisingfirst and second members extending from the pusher assembly and movablebetween a first position having a first gap dimensioned to receive thesingle use loading unit and a second position having a second gapsmaller than the first gap and dimensioned to prevent insertion of thesingle use loading unit.
 14. The surgical fastener applying apparatusaccording to claim 13, wherein the first and second members extend fromfirst and second sidewalls of the pusher assembly.
 15. The surgicalfastener applying apparatus according to claim 14, wherein the first andsecond members are normally in the second position.
 16. A disposablefiring assembly for use with a surgical fastener applying apparatuscomprising a disposable single use loading unit and a disposable pusherassembly, the pusher assembly insertable into a cartridge receiving halfsection of the fastener applying apparatus, the single use loading unitoperably mountable to the pusher assembly, wherein the pusher assemblyincludes a lockout member movable from a first position preventingoperable insertion of the single use loading unit therein and a secondposition enabling operable insertion of the single use loading unittherein.
 17. The disposable firing assembly according to claim 16,wherein the lockout member is normally in the first position and thelockout member is prevented from moving to the second position when thepusher assembly is mounted within the cartridge receiving half section.18. The disposable firing assembly according to claim 16, wherein thelockout member includes first and second members extending inwardlytoward a longitudinal axis of the pusher assembly and movable to vary agap therebetween.
 19. The disposable firing assembly according to claim16, wherein the first and second members pivot from a first positionsubstantially perpendicular to the longitudinal axis corresponding tothe first position of the lockout member and a second position inclinedwith respect to the longitudinal axis corresponding to the secondposition of the lockout member.